1. Technical Field
The present technology relates to a pneumatic run flat tire and more particularly relates to a pneumatic run flat tire by which riding comfort when regular traveling can be maintained at a high level and run-flat durability can be enhanced.
2. Related Art
With pneumatic tires, a side-reinforced pneumatic run flat tire in which a reinforcing rubber layer having a falcated cross-section is inserted on an inner face of a side wall portion, and by which run-flat traveling is made possible based on the rigidity of this reinforcing rubber layer is known (e.g. see Japanese Unexamined Patent Application Publication No. 2010-023823A). With such a side-reinforced pneumatic run flat tire, there is a benefit in that run-flat traveling is achieved based on the tire structure without depending on a support body such as an inner ring or the like attached to the wheel, but there is also a problem in that the rigidity of the side wall portion is higher than that of a regular tire and, therefore, riding comfort when regular traveling is negatively affected.
Therefore, in recent years, what are referred to as “soft run-flat tires” have been used in which the same degree of riding comfort as in a tire that does not have a reinforcing rubber layer is maintained while at least the minimum necessary run-flat durability is ensured by miniaturizing the reinforcing rubber layer as much as possible without inhibiting run-flat durability or reducing the rigidity. However, with such a run flat tire in which the reinforcing rubber layer is miniaturized or the rigidity thereof is reduced, the run-flat durability may decline severely, and there remains room for improvement in achieving both run-flat durability and riding comfort when regular traveling.
Additionally, when mounting such a run flat tire on a vehicle provided with a camber angle, and particularly when mounting the run flat tire on a vehicle provided with a negative camber angle, there is a problem in that it is difficult to ensure run-flat durability because the side wall portion positioned on a vehicle inner side is subjected to a large load.